REPRESENTATIVES FROM THE CITY OF PHILADELPHIA, THE CRIMINAL JUSTICE SYSTEM, THE NATIONAL COUNCIL ON ALCOHOLISM-DELAWARE VALLEY AREA, AND AN ALCOHOLISM TREATMENT PROGRAM FROM A LARGE INNER-CITY COMMUNITY MENTAL HEALTH CENTER ESTABLISHED AN INTERAGENCY RELATIONSHIP THAT ALLOWED PHILADELPHIA TO PROVIDE AN ALTERNATIVE MECHANISM FOR MANAGING THE PROBLEMS OF DWI OFFENDERS. BEFORE INITIATING THIS COOPERATIVE EFFORT, ALL DWI OFFENDERS WERE THE RESPONSIBILITY OF THE CRIMINAL JUSTICE SYSTEM AND LITTLE OR NO EFFORT WAS MADE TO UNDERSTAND THE COMPLEX RELATIONSHIP BETWEEN ALCOHOL CONSUMPTION AND DRIVING. TWO PRINCIPAL SOURCES OF DATA WERE USED TO STANDARDIZE THE STUDY OF DWI FIRST OFFENDERS: (1) CLIENT INTAKE FORM, AN INTERVIEW FORM ADMINISTERED TO RECORD ALCOHOL IMPAIRMENT, DEMOGRAPHIC AND SOCIOECONOMIC BACKGROUND, FAMILY DRINKING PATTERN, AND OTHER PERTINENT SOCIAL INFORMATION; AND (2) HOME INTERVIEW FORM, AN INTERVIEW FORM ADMINISTERED TO THE SPOUSE (IF ANY) OF CLIENTS INITIALLY SEEN FOR EVALUATION. A SPECIALIZED DWI ELEMENT, THE PSYCHOSOCIAL EVALUATION UNIT, WAS DEVELOPED TO CONDUCT SYSTEMATIC INVESTIGATIONS OF THE BEHAVIOR AND BACKGROUND OF COURT-REFERRED DWI OFFENDERS. AN ALCOHOL IMPAIRMENT INDEX WAS FORMULATED FOR THREE GROUPS IN ASCENDING ORDER OF SEVERITY OF DRINKING: (1) PERSONS WHO TYPICALLY CONSUME ALCOHOLIC BEVERAGES IN SOCIAL SITUATIONS, ONCE OR TWICE A DAY UP TO A LIMIT; (2) PERSONS WHO CONSUME ALCOHOL HEAVILY AT LEAST TWICE WEEKLY, WITH OCCASIONAL PROLONGED PERIODS OF DRINKING AND REPORTED MEMORY LAPSES; AND (3) HEAVILY CONSUME ALCOHOLIC BEVERAGES DAILY, BEGINNING UPON AWAKING, WITH MISSED MEALS, MEMORY IMPAIRMENT, AND ARRESTS FOR FIGHTING OR PUBLIC INTOXICATION. OF 1,500 FIRST DWI OFFENDERS ARRESTED, 685 WERE IN THE FIRST GROUP, 721 WERE IN THE SECOND GROUP, AND 94 WERE IN THE THIRD GROUP. PERSONS UNDER 40 YEARS OF AGE WERE MORE ALCOHOL-IMPAIRED THAN PERSONS OVER 40 YEARS OF AGE. DRUG USERS WERE CHARACTERIZED BY A MORE SERIOUS PATTERN OF ALCOHOL ABUSE. BLACKS COMPRISED 49.5 PERCENT OF THE DWI SAMPLE AND WHITES 47.4 PERCENT. DRINKING PRACTICES IN FAMILIES PLAYED AN IMPORTANT ROLE IN DETERMINING DRINKING HABITS. THE IMPLICATIONS OF THE FINDINGS ARE DISCUSSED IN RELATION TO THE PROCESSING OF DWI OFFENDERS IN THE CRIMINAL JUSTICE SYSTEM. SUPPORTING DATA AND REFERENCES ARE INCLUDED. (DEP)